Comparison – batterybalance

Comparison of systems on the market

Features

An important and crucial parameter for a system is how much current it can handle:
1) Systems that have mechanical relays (contactors) can handle 500+ amperes. BMS has output (s) that can handle peak current of 5 – 7 A when activating the relay.
2) There are also systems that only have one output for load relay and then remotely control the chargers.
3) Simplified systems that can not control mechanical relays but instead MOSFET-based SSR. These systems can handle lower currents and have lower reliability.

Another difference between systems is balancing:
A) Central and controlled by a master unit.
This balancing can be passive or active and controlled by an algorithm.

B) Balancing boards connected in a daisy chain
Most balancing boards have a simplified principle which means that balancing starts as soon as a cell exceeds a certain voltage when the battery is fully charged. When all cells exceed this voltage, they are all balanced equally even if the cells have different voltages. This means that the balancing will be completely without effect if all cells are balanced / shunted equally. This type of balancing is less efficient and requires a high balancing current to have any effect. High balance current also creates issues with strong heat on the cell boards.

*) Comparison of Others are all manufactures which offer 12/24 V batteries with BMS, as well as all standalone BMS manufactures, which are available in the market year 2019 – 2020.

**) Lithionics offering BMS included in their batteries, which has 2-level protection and AFD (named FCC). However, Lithionics has discontinued standby current from cell-boards and protection at lower cell voltage.

***) Victron has launched a new feature to get a signal as pre-alarm, however needs an external device (not sold by Victron) and is only one-level indicator of voltage (about 5-7% SOC) but can be as short as 30 seconds previous LVP shut down.

****) Mastervolt has pulse-control of latching contactor, however not a dual system which means if this single contactor disconnects as protection for overcharging or error, it will result in blackout.

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